Superficial blood vessels of the conjunctiva that overlie the sclera are a cosmetic source of dissatisfaction among millions of people. These blood vessels vary in size, length, and number. Often such blood vessels are unsightly and lead to diminished self-esteem or even social stigma. People with large numbers of such vessels may appear tired or fatigued to others, affecting the perception of co-workers, supervisors, family, and friends. Therefore, people with such blood vessels may desire whiter appearing eyes for improved cosmesis. Currently there is no permanent treatment for such problems.
Lasers are used for the targeted treatment of hemoglobin in blood vessels, but lasers can easily penetrate through the sclera and are dangerous to inner ocular structures such as the choroids and retina. Surgical vein stripping in theory is possible, but it is not performed due to the invasiveness of the procedure. Temporary treatments exist for conjunctival blood vessels in the form of pharmaceutical eye drops that contain vasoconstrictive agents. However, these agents typically last 3-6 hours and require reapplication. When such medicated drops are discontinued, the rebound effect can lead to worsening of conjunctival injection and vascular engorgement. The widespread use of such topical eye drops reflects the need for a permanent solution to this widespread problem. A similar problem exists with superficial lesions of the conjunctiva, such as brown nevi, yellow pinguecula, pigmented tumors, and other structures that can be cosmetically unattractive. The only permanent treatment is invasive surgical removal.
Blepharitis is a common condition of the eyelids that causes ocular discomfort and may lead to dry eyes, corneal scarring, and loss of vision. Blepharitis is the result of dysfunctional meibomian glands of the eyelids that result from vascular engorgement at the margins. There is no known cure for blepharitis, only palliative treatments such as warm compresses and eyelid massage. Oral doxycycline can be used to control blepharitis, but such medication has side effects such as skin sensitivity to the sun, gastritis, esophageal ulcer, and diarrhea. Steroidal eye drops have also been used to control the problem, but also have deleterious side effects such cataracts and glaucoma.
Trichiasis is a condition of misdirected eyelashes that grow towards the eye instead of away from it. Trichiasis can be a chronic source of foreign body sensation, tearing, and cornea trauma.
For the last decade, intense pulsed light (IPL) has been used in dermatology to treat vascular and pigmented lesions of the skin. A relatively recent review of IPL appears in Raulin, MD, Christian et al, Lasers In Surgery And Medicine, IPL Technology: A Review, 32:78-87 (2003). IPL systems utilize a source that emits pulsed polychromatic light in a broad wavelength spectrum of 515-1200 nm. Utilizing selected wavelengths can heat and eliminate target structures such as varicose veins or pigmented skin. Hemoglobin largely absorbs at a wavelength of approximately 580 nm, and brown structures such as melanin absorb in the range of about 400 to 750 nm. Filters are used to allow the optimal wavelength to penetrate the tissue, thereby essentially heating only the target structure to the desired degree that causes the structure to disappear. The pulse duration, typically in milliseconds, can also be adjusted so that it is lower than the thermal relaxation time of the targeted structure. This avoids damage to the adjacent tissue. The interval between pulses, also in milliseconds, can be adjusted as well. The delay allows heat to decrease in adjacent tissue, while heat is maintained in target tissue. IPL treatment has proven effective for the treatment of vascular lesions of the skin, including benign venous formations, telangiectasias, hemangiomas, and port-wine stains. Pigmented lesions of the skin, such as macules, nevi, and melasma also effectively respond to IPL.
The light for IPL treatments is typically generated in a relatively large console that may or may not be mobile. The treatment is applied via a bulky, handheld head that is adapted for the exchange of different filter-coated crystals that select for desired wavelengths. One example of such a device is the Vasculight™ Intense Pulsed Light and Laser by Lumenis. A smaller version of an IPL device is the Quadra Q4 Platinum Series by DermaMed USA, Inc. Because IPL was specifically designed for use in dermatology, the present head design and filter-coated crystals are not suitable for the ocular application of IPL treatments. Heads currently in use typically require the user to grasp a large handle with four fingers and thumb, similar to grasping portable electric devices like a drill or mixer, or even grasping the handle on a briefcase. This configuration does not allow for precise maneuvering and control of the head to treat small structures in the eye or eyelid. Such design also precludes use of the head with a slitlamp microscope, which would be needed to accurately apply IPL to ocular structures.
The filter-coated crystals used in dermatology are also not suitable for ocular application, because they are too large and would apply IPL treatment to other ocular structures not requiring treatment. The smallest crystal dimension currently appears to be 8 mm, which is considered small for skin treatments, but is too large for application in ocular surface and eyelid treatments. Moreover, the large size of IPL heads prevents the operator from maintaining a precise, constant distance from the target structure. Typically, in dermatological use, a cool gel is applied to the skin, the upper surface of which is a few millimeters above the skin. The end of the crystal in the head is then held at the top of the gel, preferably not contacting the skin. Because of the cumbersome nature of the head, and the lack of any guiding or measuring device at the end of the crystal, the crystal may momentarily touch the skin or may move a significant distance above the top of the gel. Experience provides operators with a steady hand and a better sense of distance, but for ocular use of IPL more precision would still be required.
In an effort to assess the dangers and difficulties of using presently available IPL equipment on ocular structures, the inventor used a Lumenis IPL™ Quantum SR to try to determine the intraocular effect from the IPL applied to the outside of the sclera. A bovine sclera, obtained from a slaughterhouse, was initially used for this purpose. The proximal side of the sclera was covered with a typical dermatological IPL gel. The IPL head was held as steadily as possible so that the end of the crystal just touched the gel, which had a thickness of approximately 3 millimeters. IPL was applied, and an electronic thermometer with a wire probe was used to determine the temperature of the distal side of the sclera. Numerous readings were taken. After each IPL application, the sclera was allowed to cool and a fresh coating of gel was applied to the sclera. The temperatures were inconsistent. The most apparent reason was the inability to hold the head steady while actuating the IPL.
Because of the cumbersome structure of IPL devices, the manufacturers conspicuously warn against use of the device in the area of the eye. Documented reports of injury to the eye from IPL make physicians and manufacturers hesitant to use IPL on the eye itself. For example, focal damage to the iris with distortion of the pupil occurred in treating a two-year old child's birthmark. Sutter, F. K., et al, Dermatology Surgery (January 2003), Ocular Complication Of PhotoDerm VL Therapy For Facial Port-Wine Stain, 29(1): 111-12. The paper concluded that such therapy could damage ocular tissues and that appropriate eye protection during the dermatological procedure was essential, even though the procedure did not involve the eye itself. Likewise, page 2-4 of the October 2002 Operator's Manual for the IPL™ Quantum SR by Lumenis states:                Intense pulsed light emission presents an eye hazard . . .        Make sure that the patient and all those present in the treatment room guard against accidental exposure to this emission either directly from the treatment head or indirectly from a reflecting surface.        Never look directly at the light beam coming from the treatment head, even when wearing Lumenis eyewear.        Never point the treatment head so that it discharges into free space.Section 2.3, pages 2-6 and 2-7, of the Operator's Manual is entitled Optical Safety and lists additional precautions that should the manufacturer suggests for operators, patients, and those in the room during application IPL.        
A recent article describes a single instance in which some success was achieved by using IPL for the treatment of dry eye. Toyos, MD, Rolando et al, Eye World (September 2005), Case Report: Dry-Eye Symptoms Improve With Intense Pulse Light Treatment, 73-74. Even in this instance, external stick-on IPL shields were applied to the patient's eye area, covering the entire eye.
After obtaining inconsistent temperature readings with the Quantum SR and the bovine sclera, it was determined that IPL temperature measurements should be taken while maintaining a constant and predetermined distance between the crystal tip and the sclera. The goal was to evaluate whether the inner sclera temperature would be below, at, or exceed 65-75° C., which is the temperature at which blood coagulates and blood vessels collapse. This knowledge is necessary because vital inner choroidal and retinal blood vessels are adjacent to the sclera wall. A microscope base was modified so that an eye could be placed on the surface where a slide is typically placed. Four threaded posts were placed around the perimeter of the slide surface. Nuts were used to adjust the height of a second flat platform with an opening in the center. In this manner, the distal end of a filter-coated crystal in the IPL head of the Quantum SR could be placed at a fixed distance above the sclera of an eye, with the IPL passing through the center opening of the second platform. The support apparatus was used with a fresh, cadaverous human eye to measure the temperature of the inner surface of the sclera after the application of IPL. The eye was obtained from an eye bank and stored in standard preservation media. Initially the eye was refrigerated and allowed to reach room temperature prior to the experiment.
In this experiment, the distance between the crystal tip and the outer surface of the sclera was fixed at 3 millimeters. A 590 nanometer filter was used, with two 7 millisecond pulses. The fluence, in joules/cm2, was varied between 20 and 60, and the time delay Δt between pulses was varied between 20 and 50 milliseconds. The skin type was set to I on the Fitzpatrick Skin Type scale. As with the bovine sclera, each reading was separated by minutes and preceded by the application of the cooled IPL cooling gel. To measure the temperature of the inner surface of the sclera, the end of the wire probe of the electronic thermometer was run through and to the tip of an 23 gauge needle. The needle was inserted into the sclera and passed through the vitreous cavity toward the opposite part of the eye globe until resistance from the underside of the sclera was felt on the needle tip. The wire tip of the electronic thermometer was then pushed through the hollow needle until inner eye wall resistance was felt against the wire tip. IPL treatments were applied to the outer sclera directly over the temperature probe. Prior to each electronic temperature reading, the wire probe was pushed back through the needle to ensure contact against the inner wall of the sclera.
The results of the second set of experiments were more encouraging than the first. The following temperatures of the inner surface of the sclera were measured.
Fluence injoules/cm22030405060Δt = 20 ms19.2° C.21.7° C.22.6° C.27.0° C.25.1° C.Δt = 20 ms20.1° C.20.2° C.23.3° C.Δt = 30 ms20.6° C.Δt = 40 ms20.3° C.Δt = 50 ms20.0° C.Two final readings were taken, one with a fluence of 20 and one with 60. Δt was 20 ms. With the crystal tip 3 mm above the sclera, the temperature of the retina was taken at approximately 180° from the cornea. There was no measurable temperature change.
The preceding data suggest that with the proper equipment and technique, the convective and conductive heat generated by IPL in the vicinity of the eye can be dealt with safely, since the temperatures were not close to the 65-75° C. threshold for blood coagulation that would affect the choroidal and retinal vessels at the inner scleral wall. Likewise, the heat absorbed by the external target structure and then conducted to adjacent tissue should not cause problems. Further study can determine the pulse durations that will still be lower than the thermal relaxation time of target structures such as conjunctival blood vessels. This will insure that excess energy is not absorbed by the sclera, thus damaging adjacent tissue or interior structures. Similarly, further study can determine the pulse intervals necessary to achieve thermal damage in the target structure while permitting the sclera or eyelid and smaller vessels to cool after the first pulse.
As presently used, however, the intensity of the pulsed light has also discouraged the use of IPL in ocular treatments. IPL is typically generated in the visible spectrum, occasionally encompassing some of the near-infrared spectrum. As seen from the preceding discussion, heat absorbed by the sclera through selective photothermolysis is far less problematic than the energy of the pulsed visible light. Without precise IPL application and eye protection, the light can pass through the cornea, burning it and the interior ocular structures behind it.
IPL has potential usefulness for treating conjunctival blood vessels and the other problems discussed above. As seen in the preceding discussion, there is a need for an apparatus and method to permanently and non-invasively treat conjunctival blood vessels, brown nevi, yellow pinguecula, pigmented lesions and tumors, and similar problems. Likewise, there is a need to better and non-invasively treat blepharitis and trichiasis. There is also a need to develop IPL equipment and methods of using it so that IPL can be used safely on the sclera and the adjacent eyelids. This includes making the application of the IPL more precise and protecting the cornea and the interior of the eye from the visible light.